Hi, buddies this is my first instructable, i hope you will learn something from this ,,
This experiment contains very basic electronics .For beginners of electronics this is very good intructable .

This security alarm use full in home appliances and at shopes etc and the same circuit can be used for many applications like 1.security alarm
2.auto door opening and close
3.auto light on and off
4. can be use with ir senosors and also in 5.light following robot

First of all i would like to say ,i made this not only for experiment but also for i recycled eletronic components which i found in broken mobile charger and other circuits
Lets start ,
1) Things i used here are

Pcb board (got from broken charger)
Ic555
Capacitors- 0.1µ f and 100µf/25v
Resistors-10k ohm and 4.7k ohm
Ldr
Wires
Soldering gun
Buzzer , light source,battery

Step 1: 2)circuit Diagram

3)connecting elements on board

connect elements on bread board or on pcb board by seeing circuit diagram its very easy to connect once you know how to connect ,. I have shown already connected circuit on pcb by me

Dont worry about it do your own its very easy

Step 2: 4)working

Whenever light falling on ldr sensor cuts by any person or object the buzzer starts ringing in such way we can use it in security

Step 3: 5)see the Video How It Works

https://youtu.be/GCcAvyvumgY
https://youtu.be/WnTzjEwo-lw

Step 4: 6) Connect the Circuit With Relay

you can use this low powered circuit to switch high AC current of 230v by connecting the out put of circuit to relay , so that you can get high sound out put
See the connection of relay with this circuit ....
(choose relay with dc of 3- 9 v and ac 230v)
The relay has 5 terminals A, B ,No(normally open), Nc (normally closed) and pole
connect relay as shown below the diod D1 is connected across A and B to avoid damage to dc circuit

you can use IR receiver diod instead of Ldr but you need to produce IR light using IR LED with series resistor